1. Field of the Invention
The present invention relates to an image forming system and an image forming apparatus.
2. Description of Related Art
In image forming apparatuses such as copying machines and printers connected to a network, it is known to provide a power-saving mode for saving power at the time of waiting a job. In the power-saving mode, for example, a fixing device is kept low in temperature.
However, even if the power-saving mode is switched to a normal operation mode by releasing the power-saving mode, the user have to wait for some time because the image output operation will start only after the temperature of the fixing roller in the fixing device has risen to a predetermined value.
Japanese Patent Laid-open Publication No. H8-320635 discloses an image forming apparatus with a power-saving mode. The image forming apparatus is provided with a human body detection sensor. In this image forming apparatus, when the sensor detects that a human body is located near the image forming apparatus, a power is supplied to the control portion and the driving portion. On the other hand, when the sensor does not detect a human body, the power source other than that of the human body sensor is turned off.
However, according to the aforementioned known structure in which a human body sensor is used to detect an existence of a human body near the image forming apparatus and it is judged whether or not the power-saving mode is to be released based on the detected results by the human body sensor, there is a possibility of misjudging that a user is located near the image forming apparatus even if another person other than the user passes near the image forming apparatus, resulting in ineffective power-saving effect. Furthermore, even if the user returns to the image forming apparatus and the human body sensor detects the user, an image output operation such as a copying operation will not start immediately. Thus, it is required to take some time until the fixing device returns to its operable temperature or the like.